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Description/Abstract

This chapter reviews the developmental pathways contributing to the origin of obesity. Evolutionary considerations are emphasized. At birth more than half of a human baby’s metabolism is devoted to the brain and it is suggested that the extreme neonatal and early childhood adiposity of humans is an adaptation to provide an energy reserve during periods of nutritional stress arising from infections and the process of weaning. This chapter also reviews the substantial experimental and clinical evidence for prenatal and early postnatal factors in the development of obesity. Developmental pathways that may lead to obesity include fetal undernutrition caused by an impaired intrauterine environment, fetal overnutrition and macrosomia caused by maternal diabetes, and infant overnutrition caused by excessive early feeding. There is evidence for interactions between these pathways and for intergenerational influences. Finally, this chapter discusses the implications for the global obesity epidemic of mismatch between the genotype, environment, and lifestyle, and underlines the potential role of inappropriate adaptive responses during development in populations undergoing rapid nutritional transition.